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The past year has provided a stark reminder of the reality we face regarding water-related disasters resulting from a changing climate. The summer and autumn of 2017 saw a string of record-breaking hurricanes engulf the U.S. Gulf Coast, eastern seaboard, Puerto Rico and the Caribbean, with significant devastation experienced by communities living in these areas.

With global temperatures already more than 1 degree Celsius above pre-industrial levels, we’re being faced with environmental changes faster and greater than ever before. Rising sea levels, storm surges and drought are the most immediate concerning results of this, especially given the proportion of the world’s population and economy potentially impacted.

Today, 54 percent of the world’s population lives in urban areas, and this is expected to increase to 66 percent by 2050. Many of these cities and towns are in low-lying coastal locations, meaning flooding threatens human life, as well as the economic, social and environmental values of urban communities. Twenty mega-cities are predicted to be located on the coast or within delta systems by 2030, with a total combined population of over 420 million people.

It is therefore vital for urban areas to consider their resilience to change across the water cycle – both in terms of protecting against water damage but also maintaining the freshwater quality and quantity required for human survival.

Last month I joined scientists, politicians, industry experts and activists to discuss these challenges on “Water Action Day” at COP23 in Bonn. Going into and emerging from the U.N. climate conference, it remains clear that changes to our water environment and our cities are the main ways climate change will be felt by people around the world. And it’s my belief that, unless “water” is properly addressed and considered, then the implementation of any global climate agreement will fail.

There remains, however, no single quick-win answer to protecting cities from changes to the water cycle. Adaptation to sea-level rise, particularly flood risk and storm surge, will require the cooperation of a number of parties across the private and public sectors.

There are a huge range of interventions, which broadly fall into the categories of protect and adapt; accommodate and recover; and retreat.

CITY CHALLENGES

Drought has posed massive challenges to Australia and the West Coast United States in recent years, and is a major headache for Cape Town.

The “protect and adapt” strategy most commonly relies on structural approaches, which are generally designed to reduce the risk of an event by decreasing its probability of occurrence (for example, flood warning, hard or natural flood defences, and adequate water supply).

The “accommodation and recover” strategy reduces the impact of sea-level rise through changes in human behaviour or infrastructure, while maintaining the use of coastal areas (for example, land use planning, building codes and water demand management).

As sea level rises and flood risk increases, evacuation or relocation away from coastal areas is likely to become an increasingly necessary adaption option. Many cities will need to decide to retreat from certain locations or relocate particular assets. For many, a combination of all three will be required. For those cities exposed to water shortages, consideration of short- to long-term actions, including water rationing and desalination, pose their own challenges to citizens.

Cities also shoulder a large responsibility for developing our world’s resilience to water and climate change. While repercussions will be felt around the world, the most immediately vulnerable cities and populations - those who are already highly exposed to extreme climate phenomena - will be the most affected. These are the same people with the least capacity to respond and adapt, and if we don’t act urgently, political and social tensions and conflicts will likely increase.

Water unites us all – our dependency on it and our vulnerability to it. It must be seen as a connecting enabler between policy areas, economic sectors and borders, and as a means to bridge trust between poor and rich countries.

Ultimately, coordinated action is needed now to increase visibility for water within the Global Climate Action Agenda – because, make no mistake, the decisions made today will set the trajectory for generations to come.